Browse Prior Art Database

COMA IN A TILTED CYLINDER MIRROR

IP.com Disclosure Number: IPCOM000025546D
Original Publication Date: 1986-Feb-28
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 75K

Publishing Venue

Xerox Disclosure Journal

Abstract

U.S. Patent 4,247,I 60 - "Scanner with Reflective Pyramid Error Compensation", by Harry P. Brueggemann, issued January 27, 1981, discloses a method of obtaining wobble correction with cylindrical optical element without introducing cross-scan curvature. This was done by using a mirror instead of a glass lens, as disclosed in the patent but a mirror returns the rays in the direction that they came from and the possibility exists of interfering with other optical elements. Interference is avoided by tilting the mirror, as shown in Figures 2 and 4 of the patent,

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XEROX DISCLOSURE JOURNAL

COMA IN A TILTED CYLINDER MIRROR

CIassif Proposed Harry P. Brueggemann ication

U.S. CI. 350/6.8 Int. C1. G02b 26/08

U.S. Patent 4,247,I 60 - "Scanner with Reflective Pyramid Error Compensation", by Harry P. Brueggemann, issued January 27, 1981, discloses a method of obtaining wobble correction with cylindrical optical element without introducing cross-scan curvature. This was done by using a mirror instead of a glass lens, as disclosed in the patent but a mirror returns the rays in the direction that they came from and the possibility exists of interfering with other optical elements. Interference is avoided by tilting the mirror, as shown in Figures 2 and 4 of the patent,

When a mirror is tilted, the aberration of coma is introduced in the direction of tilt. This coma is proportional to the angle of tilt, and inversely proportional to the square of the f/number of the beam. The scanner systems typical at the time the patent was filed had spot diameters of 1.5 to 3 mils at the photoreceptor, corresponding to f/numbers of f/100 to f/200. With these large f/numbers, coma due to mirror tilt was significant, and was ignored.

Presently, however, high resolution scanner systems are being designed with spot diameters of 0.25 to 0.5 mils, and the corresponding flnurnbers are f/16 to f/32. Being proportional to the inverse square of the f/number, coma due to rnirror tilt is 40 to 150 times larger than in the low resolution systems, and cannot be i...